Polyurethane resins are usually produced by a reaction between a polyisocyanate component and a polyol component, and are widely used in various fields of industry, for example, as elastomers, lenses, synthetic leather, slush powders, elastic molded articles (spandex), RIM molded articles, paints, adhesives, sealing materials, or foams.
As the polyisocyanate component, although aromatic diisocyanate such as tolylene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI) is industrially well-known, aliphatic and alicyclic diisocyanates such as hexamethylene diisocyanate (HDI), 3-isocyanatomethyl-3,5,5-trimethyl cyclohexylisocyanate (IPDI), further dicyclohexylmethane diisocyanate (hydrogenated MDI), or bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), are widespread in the fields where yellowing resistance is required.
Among them, bis(isocyanatomethyl)cyclohexane is excellent in yellowing resistance and mechanical properties, and further use thereof is expected in future.
Bis(isocyanatomethyl)cyclohexane includes structural isomers of 1,3-bis(isocyanatomethyl)cyclohexane and 1,4-bis(isocyanatomethyl)cyclohexane, and further, geometric isomers designated as the trans isomer and the cis isomer are known to exist in each of 1,3-bis(isocyanatomethyl)cyclohexane and 1,4-bis(isocyanatomethyl)cyclohexane.
There has been reported that, for example, 1,4-bis(aminomethyl)cyclohexane having a content ratio of trans- to cis-isomer of 3.3:1 (i.e., 77% by mole of trans isomers) is phosgenated to synthesize 1,4-bis(isocyanatomethyl)cyclohexane containing 77% by mole of trans isomers, and the 1,4-bis(isocyanatomethyl)cyclohexane is used to synthesize an elastomer (see, for example, the following Patent Document 1).    Patent Document 1: U.S. Pat. No. 4,565,835